Fixed bug in CalculateDay()

Using PermittedLogonTimes.GetLogonTimes() I was getting strange results for the DayOfWeek properties of the resulting LogonTimes.

Stepping through the code it seems that CalculateDay() was incorrectly dividing the index by 7 days instead of 24 hours.

Changing this seems to work for me, although I will admit I haven't done extensive testing on the impact of the change.